P1.20 Clinical features of limb-girdle muscular dystrophy type 2B with the c.2997G > T mutation

Background: Dysferlinopathy refers to a group of autosomal recessive muscular dystrophies caused by mutations in DYSF, which encodes dysferlin working for calcium-dependent membrane repair in skeletal muscle. The disease group includes three distinct disorders; limb-girdle muscular dystrophy type 2B (LGMD2B), Miyoshi myopathy (MM) and distal anterior compartment myopathy. Since dysferlinopathy is considered as a relatively common cause of muscular dystrophy in Korea, it is needed to characterize clinical and genetic features in Korean patients of dysferlinopathy. Methods: The patientswere recruited for this study based on the finding of complete loss of dysferlin immunoreactivity from database of two major muscle research centers in Korea. The patients’ genotypes were analyzed by directly sequencing the DYSF using their whole blood or frozen muscle tissues. For clinical characterization, patients’ data were retrospectively reviewed. Results: A total of 21 patients (13 men and 8 women) proved to have 19 different mutations including 10 novel ones. Thirteen were missense mutations and 6 were small insertion/ deletion. The mutation of c.2494C > T had high allele frequency (9/ 42) and c.663 + 1G > C was followed (6/42). In clinical aspect, 19 patients were compatible with MM while only two were identified as LGMD2B. Muscle CT well delineated the characteristic muscle involvement in each disorder. Serum CK was very high in all patients irrespective of the disease. Conclusion: This study demonstrates a strong ethnic specificity in Korean patients with dysferlinopathy, and some part of whichwas sharedwith Japanese population. Clinical features were similar to the previous reports showing late onset age, prominent calf muscle atrophy in MM and high serum CK.